Synonyms
Rhesus, rhesus factor, blood groups
Introduction
The rhesus factor is, similar to the AB0 blood group system, a classification of blood groups determined by proteins on the surface of red blood cells (erythrocytes). Like all cells, red blood cells contain a large number of protein molecules against which the body’s immune responses can be directed. Five different proteins are called rhesus factor: C, c, D, E and e (as a continuation of blood groups A and B).
C and c, as well as E and e are different protein molecules, whereas d only describes the absence of D. Depending on the hereditary disposition, different combinations of these proteins (which, since they can also be the target of a defense reaction by antibodies, are also called antigens) can be produced. Inheritance is similar to the AB0 system. Each person receives from father and mother one variant C (C or c), D (D or no D, which is called d) and E (E or e), which together determine the rhesus blood group.
Since complex transcription, e.g. CcDDee (from one parent C, from the other c, from both D and e) is not always necessary in everyday clinical practice, and the factor D is the most important, one often limits oneself to the simplification Rhesus-positive (Rh(D)+, Rh+ or Rh) or Rhesus-negative blood (Rh(D)-, Rh- or rh), which in each case only describes the presence or absence of the factor D. A person who has inherited factor D from at least one parent (e.g. CcDdee or CCDDEE) is therefore called Rhesus positive. Only a person who has not inherited factor D from any parent (e.g. CCddEe) is Rhesus negative.
History
The rhesus system was discovered jointly in 1937 by the Austrian Karl Landsteiner and the American Alexander Solomon Wiener. Landsteiner had already discovered the AB0 system in 1901 and was awarded the Nobel Prize for Medicine in 1930. Since they succeeded in discovering the blood group characteristics during research on rhesus monkeys, the name Rhesus System or “Rhesus Factor” for factor D was created.
